Arion SDI-1 Distortion Mod Project (in progress)

[asmith]

Well, it will be in progress.

Having run solely through my 30W Crate's overdrive channel for the best part of five or six years, I dug out my old Arion SDI-1 Distortion pedal, bought for me when I was but a nipper. No matter how rose-tinted the glasses might be, the pedal sounded nasty. A real nasal, overly trebled sound, with no depth or warmth, and a lot of noise. It sounded like playing radio static.

I rang up Jonny Greenwood to see if he could make an album with it about listening to untuned long-wave frequencies in a dark room to be 'artistic,' but it turns out he builds his own pedals and doesn't need a cheap Japanese pedal. Thanks all the same.

Let's do some modding then. I've just jumped headfirst into the world of screwing about with the wires in my guitar; seize the zeitgeist. Bugger up something else.

A couple of unscrewings later, I've got a circuitboard on my hands. It looks a lot more complicated than some of the examples on this page.

Now, I can input every component into 5Spice (cheers JohnH and ashcatlt) individually and do a whole lot of sharp-curve learning, or I can avoid the risk of losing my sanity. What's the use in playing the guitar if you end up like this chap?

I've searched, googled, followed links and hired a private detective but I still can't find a schematic for the SDI-1 pedal to pore over and try to make sense of before I jump in there. I think it's much better not only for the project but also for my understanding of the whole electronics caboodle that I sit with the schematic until I understand completely what the hell is going on inside this plastic box of Eartha Kitt.

Does anybody have a schematic, can point me in the right direction, or even share tidbits of info that would be of great help before I embark on this hairbrained scheme?

[flateric]

You'll find a sd1 schematic with a bit of googling. Meanwhile here's some info on mods for the SD1:

www.erikhansen.net/pedalmods.php

Googling SD-1 mods will give you more useful info

[ashcatlt]

Can you shoot a couple of well lighted and focused photos of both sides of the PCB?

[JohnH]

Maybe it could do with an extra stage of eq, at the end of the circuit. If you record some into your pc, then we could try some different eq curves on it to boost the low end and/or trim the highs. Then a simple filter network can be designed to achieve that result. You wont need to know everything about the original circuit since this would be a freestanding stage at the end. Are you up for that? if you can post a sound clip, you might get a few return ideas of how it might sound posted back.

I used the same approach to design a preamp for my piezo pickup - ie, recorded a sound, eq'd it in the pc, then made a circuit to achieve that EQ.

John

[asmith]

Not a problem. Here's a demonstration of the pedal.

Clean channel	No Distortion	N/A	00:31
Soft channel	Full Distortion	Full Tone	00:49
Soft channel	Full Distortion	Mid Tone	01:08
Soft channel	Full Distortion	Low Tone	01:22
Soft channel	Mid Distortion	Full Tone	01:48
Soft channel	Mid Distortion	Mid Tone	01:55
Soft channel	Mid Distortion	Low Tone	02:09
Direct channel	Full Distortion	Full Tone	02:32
Direct channel	Full Distortion	Mid Tone	02:46
Direct channel	Full Distortion	Low Tone	03:13
Direct channel	Mid Distortion	Full Tone	03:32
Direct channel	Mid Distortion	Mid Tone	03:52
Direct channel	Mid Distortion	Low Tone	04:11

Here's some circuitboard pics as well. My digital camera seems to be broken - it's many years old after all. These are the best I could muster on my phone. I'm as frustrated as you are, not that that makes a difference.

[JohnH]

Nice noodling, but that is a harsh sounding box! How was the recording done?, was it direct from box to mixer/pc?, or is it miced off an amp? The mid tone settings seem like the best basis, but it will be interesting to experiment with further EQ.

[cynical1]

I'm with John on the mid tone being your best sound out of the pedal. I would tend to agree with your that there is a risk of people in the first three rows bleeding from the ears if you used single coils with it...

My first thought is to try it through an effects loop to where you can tone it down a bit...

I'll be interested to hear what what the guru's make from this.

HTC1

[asmith]

I used a SM58 knockoff (cardioid dynamic microphone) to record the whole thing - the beeps simply indicate where I've edited out things like me pulling the mic from directly in front of the speaker up to my face to describe what's going on.

I like the mid-tone the best as well - hence I get carried away on it. I'm hoping that with a bit of extra poking around, I'll be able to replace a few caps and resistors here and there to generally de-harsh the box so that the current 'mid-tone' setting becomes just below the 'full-tone' setting, and open up the tone control so that it affects the tone in a more pleasing way. At the moment it sounds like somebody's trying to muffle a screaming victim when the tone's all the way down.

I'd also like to increase the range of distortion, as there's not much difference between the mid and full settings. And there's little difference between the 'Direct' and 'Soft' settings as well, I'd like to change that.

I'm slowly coming to terms with the circuitry of the pedal, and from what I understand, these mods ought to be confined to simple changes in the values of the parts, instead of having to rewire the circuit somewhat. Stop me if I'm wrong please.

And I'm probably going to have to rehouse the thing when I'm done too - I had to turn the thing on and off by poking through the casing with a novelty pen.